X-ray spectroscopy of heterocyclic biochemicals: xanthine, hypoxanthine, and caffeine

The electronic structures of the purine derivatives xanthine, hypoxanthine and caffeine have been investigated in the gas phase using C, N, and O 1s X-ray photoemission (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The results have been interpreted by means of ab initio calculations using the third-order algebraic-diagrammatic construction (ADC(3)) method for the one-particle Green's function and the second-order ADC method (ADC(2)) for the polarization propagator. The carbon, nitrogen and oxygen K-edge NEXAFS spectra of xanthine and caffeine are very similar, since the molecules differ only by substitution of three hydrogen atoms by methyl groups. For hypoxanthine, the electronic structure and spectra differ considerably from xanthine as the purine ring is more highly conjugated, and there is one less oxo group. Effects due to oxo-hydroxy tautomerism were not observed. However, the two oxo tautomeric forms of hypoxanthine oxo-N(9)-H and oxo-N(7)-H are populated in the gas phase, and the C 1s spectra can be simulated only by taking account of these two tautomers, with appropriate Boltzmann population ratios which we have also calculated. For xanthine and caffeine, single tautomeric forms were observed.     

Strategies for evaluation of enveloped virus inactivation in red cell concentrates using hypericin

Photodynamically induced virus inactivation appears promising in preventing transmission of enveloped virus infections in transfusible blood products. The potential for utilizing hypericin as a photosensitizer to inactivate key enveloped viruses in packed red cell concentrates (PRC) was evaluated. In addition to inactivating effectively > or = 10(6) TCID50 of human immunodeficiency virus (HIV), inactivation of bovine viral diarrhea virus (BVDV) in PRC was used as a model for hepatitis C virus to overcome the deficiency in reliable experimental systems for hepatitis C virus (HCV) inactivation. BVDV was two orders of magnitude more sensitive to inactivation by hypericin than HIV. As part of the virucidal efficacy analyses, the effects of photosensitization on hemopoietic cell lines carrying quiescent integrated HIV provirus were studied as models for evaluating virus inactivation in latently infected cells. Phorbol ester-induced virus production by these cells was effectively prevented by photosensitization with hypericin. A refinement of the illumination conditions, incorporating a monochromatic sodium light source with an emission spectrum coinciding with the absorption peak of hypericin, was highly virucidal, however, caused unacceptable levels of hemolysis. Red blood cells could be protected from phototoxic cellular damage by complexing hypericin with human serum albumin (albumin-hypericin), but the decrease in hemolysis was at the expense of virucidal efficacy. Thus, excitation of hypericin with a fluorescent source appears to be useful potentially for virus inactivation in PRC.     

The current status and future of medical laboratory quality regulation and accreditation in Ghana

High-quality and reliable laboratory services are important components of effective and well-functioning health systems. Accurate, reliable and timely medical laboratory testing is crucial to patient care and disease surveillance. Unfortunately, in many sub-Saharan African countries, medical laboratory systems are adversely affected by the unavailability of medical laboratories, poor laboratory infrastructure and lack of well-trained personnel [1]. Quality in the laboratory is only achieved in a systematic way through the implementation of a quality management system. The results of the study showed that approximately 60?% of the 78 respondents were unaware of the requirements of ISO 15189:2007. A trial of proficiency testing, termed ??blind proficiency testing??, was carried out in which 19 laboratories determined the concentrations of urea and cholesterol in a proficiency testing material. Of the 19 laboratories that determined the concentration of urea, 63?% produced satisfactory results with scores between ?2 and +2. Similarly, 63?% of the participating laboratories obtained satisfactory z scores for cholesterol determination. Some of the laboratories that obtained satisfactory scores for urea determination had unsatisfactory scores for cholesterol determination and vice versa. It is recommended that the Ghanaian government pass a law and establish a standard to regulate medical laboratories in Ghana in order to improve quality in a significant way.     

Synthesis and characterization of high-integrity solid-contact polymeric ion sensors

High-integrity solid-contact (SC) polymeric ion sensors have been produced by using spin casting and electropolymerization techniques in the preparation of the SC employing the conductive polymer, poly(3-octylthiophene) (POT). The physical and chemical integrity of the POT SCs have been evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS). Furthermore, the electrochemical stability of SC polymeric ion sensors has been investigated using electrochemical impedance spectroscopy (EIS). The results of this study demonstrate that electropolymerization and spin casting methods also comprising annealing of the synthesized SC film are capable of producing SCs that are relatively free of imperfections such as pores and pinholes. This leads to electrochemically stable and robust polymeric ion sensors where the SC/sensor interface is resistant to the formation of a detrimental water layer that normally gives rise to spurious ion fluxes and a degradation in the sensitivity and selectivity of the SC polymeric ion sensor.     

Development of simultaneous frequency- and time-resolved coherent anti-Stokes Raman scattering for ultrafast detection of molecular Raman spectra

The development of a time-resolved coherent anti-Stokes Raman scattering (CARS) variant for use as a probe of excited electronic state Raman-active modes following excitation with an ultrafast pump pulse is detailed. Application of this technique involves a combination of broadband fs-time scale pulses and a narrowband pulse of ps duration that allows multiplexed detection of the CARS signal, permitting direct observation of molecular Raman frequencies and intensities with time resolution dictated by the broadband pulses. Thus, this nonlinear optical probe, designated fs/ps CARS, is suitable for observation of Raman spectral evolution following excitation with a pump pulse. Because of the spatial separation of the CARS output signal relative to the three input beams inherent in a folded BOXCARS arrangement, this technique is particularly amenable to probing low-frequency vibrational modes, which play a significant role in accepting vibrational energy during intramolecular vibrational energy redistribution within electronically excited states. Additionally, this spatial separation allows discrimination against strong fluorescence signal, as demonstrated in the case of rhodamine 6G.     

Group-selective antibodies based fluorescence immunoassay for monitoring opiate drugs

A novel carboxylic acid derivative of monoacetylmorphine (MAM-COOH) was synthesized and conjugated with bovine serum albumin (BSA) for generating polyclonal antibodies against the target molecule heroin and its major metabolites. The conjugate was characterized by fluorescence spectroscopy, polyacrylamide gel electrophoresis, and mass spectrometry to confirm the extent of haptenization of the carrier protein. A high titer (1:64,0000) of antibody was obtained by using the conjugate with an optimum protein/hapten molar ratio of 1:100. The generated antibody showed good binding affinity with heroin and its metabolites monoacetylmorphine (MAM) and morphine. The relative affinity constant (K (aff)) of the antibody was 3.1 x 10(7) l mol(-1), and the IC(50) values obtained for heroin, MAM, morphine, and codeine were 0.01, 0.013, 0.012, and 0.014 ng ml(-1), respectively. A fluorescence-based competitive inhibition immunoassay procedure was developed for the estimation of heroin and its major metabolites in standard and biofludic samples over a concentration range up to 0.01 ng ml(-1) with good signal reproducibility (p < 0.05). The method can be used as a convenient quantitative tool for the sensitive screening of major metabolites of heroin in biological samples.     

In situ growth of epitaxial cerium tungstate (100) thin films

The deposition of ceria on a preoxidized W(110) crystal at 870 K has been studied in situ by photoelectron spectroscopy and low-energy electron diffraction. Formation of an epitaxial layer of crystalline cerium tungstate Ce(6)WO(12)(100), with the metals in the Ce(3+) and W(6+) chemical states, has been observed. The interface between the tungsten substrate and the tungstate film consists of WO suboxide. At thicknesses above 0.89 nm, cerium dioxide grows on the surface of Ce(6)WO(12), favoured by the limited diffusion of tungsten from the substrate.     

Activation of Hsp90 Enzymatic Activity and Conformational Dynamics through Rationally Designed Allosteric Ligands

Hsp90 is a molecular chaperone of pivotal importance for multiple cell pathways. ATP‐regulated internal dynamics are critical for its function and current pharmacological approaches block the chaperone with ATP‐competitive inhibitors. Herein, a general approach to perturb Hsp90 through design of new allosteric ligands aimed at modulating its functional dynamics is proposed. Based on the characterization of a first set of 2‐phenylbenzofurans showing stimulatory effects on Hsp90 ATPase and conformational dynamics, new ligands were developed that activate Hsp90 by targeting an allosteric site, located 65 Å from the active site. Specifically, analysis of protein responses to first‐generation activators was exploited to guide the design of novel derivatives with improved ability to stimulate ATP hydrolysis. The molecules’ effects on Hsp90 enzymatic, conformational, co‐chaperone and client‐binding properties were characterized through biochemical, biophysical and cellular approaches. These designed probes act as allosteric activators of the chaperone and affect the viability of cancer cell lines for which proper functioning of Hsp90 is necessary.     

Assessment of Anti-Inflammatory and Antimicrobial Potential of Ethanolic Extract of Woodfordia fruticosa Flowers: GC-MS Analysis

Currently, the potential utilization of natural plant-derived extracts for medicinal and therapeutic purposes has increased remarkably. The current study, therefore, aimed to assess the antimicrobial and anti-inflammatory activity of modified solvent evaporation-assisted ethanolic extract of Woodfordia fruticosa flowers. For viable use of the extract, qualitative analysis of phytochemicals and their identification was carried out by gas chromatography–mass spectroscopy. Analysis revealed that phenolic (65.62 ± 0.05 mg/g), flavonoid (62.82 ± 0.07 mg/g), and ascorbic acid (52.46 ± 0.1 mg/g) components were present in high amounts, while β-carotene (62.92 ± 0.02 µg/mg) and lycopene (60.42 ± 0.8 µg/mg) were present in lower amounts. The antimicrobial proficiency of modified solvent-assisted extract was evaluated against four pathogenic bacterial and one fungal strain, namely Staphylococcus aureus (MTCC 3160), Klebsiella pneumoniae (MTCC 3384), Pseudomonas aeruginosa (MTCC 2295), and Salmonella typhimurium (MTCC 1254), and Candida albicans (MTCC 183), respectively. The zone of inhibition was comparable to antibiotics streptomycin and amphotericin were used as a positive control for pathogenic bacterial and fungal strains. The extract showed significantly higher (p < 0.05) anti-inflammatory activity during the albumin denaturation assay (43.56–86.59%) and HRBC membrane stabilization assay (43.62–87.69%). The extract showed significantly (p < 0.05) higher DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging assay and the obtained results are comparable with BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene) with percentage inhibitions of 82.46%, 83.34%, and 84.23%, respectively. Therefore, the obtained results concluded that ethanolic extract of Woodfordia fruticosa flowers could be utilized as a magnificent source of phenols used for the manufacturing of value-added food products.